Just want to say that those are some excellent posts by Lady of McCamley and I would echo most of what she says. My only disagreement would be about vaccination as I am not a fan of the Marek's vaccine. It generates a false sense of security as well as potentially invites more aggressive strains of the disease to evolve. You also need to practice very strict biosecurity for 2-3 weeks after vaccinating chicks which means remembering to cover hair, wash hands and face and change clothes and shoes between the main flock and handling the chicks.... difficult if just one person is involved but if there are multiple people tending chicks and lets face it, everyone wants to handle chicks, it is quite difficult to enforce and may be why vaccinated birds still get the disease.